One of the questions raised about the mechanism of action of adoptive immunotherapy is whether the adoptively transferred cells exert their antitumor effects directly at the site of the tumor or indirectly, through the induction of secondary cytokines. In an effort to study this question, we radiolabeled LAK cells and studied their trafficking patterns as part of a prior BRMP protocol. We demonstrated that radiolabeling was technically feasible and did not affect LAK cell function. Good quality images were obtained in all patients. Radiolabeled LAK cells did not traffic to tumor sites in any patient. We conclude that the alterations made in this protocol, i.e. giving low dose cyclophosphamide and doxorubicin, or incubating LAK cells for only two days did not change the known trafficking pattern of LAK cells.